System of active ballistic protection

ABSTRACT

A system of active ballistic protection formed by at least a panel ( 1 ) comprising at least two external metallic layers ( 2,3 ) between which a layer of energetic material ( 4 ) is inserted, characterized in that said energetic material is obtained from a weakened detonating material.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of copending U.S. patent application Ser. No. 12/816,895, filed Jun. 16, 2010, entitled “SYSTEM OF ACTIVE BALLISTIC PROTECTION,” which claims the benefit of earlier filed Italian Patent Application No. TO2009A000458, filed Jun. 16, 2009, the disclosures of which are incorporated herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention refers to a system of active ballistic protection. In particular, the present invention refers to a system of active ballistic protection, also called active armor usable for the protection of armored vehicles or for fixed stations which can be subject to attacks with firearms.

2. Relevant Technology

The typical configuration of reactive armors is constituted by front and rear stratifications which have the purpose of mechanically opposing to the menace and by an intermediate stratification which has the purpose of accelerating the most external screen. The energy characterization of the intermediate stratification can be subdivided into three main categories.

In a first category, the energetic layer is constituted by an explosive. This configuration is the most efficient reactive armor.

In a second category, the intermediate energetic layer is constituted by an energetic material which lacks the capacity of detonating. This category has an efficacy lower than the first category.

In the third category, the intermediate layer is constituted by non-energetic material which, depending on its chemical-physical characteristics, is able to accelerate the most external layer of the reactive sandwich, but has less efficiency than the first and second categories.

SUMMARY OF THE INVENTION

The present invention proposes to achieve a system of active ballistic protection formed by at least two external metallic layers between which is inserted at least one layer of energetic material which, when reached by metal or other material that penetrates into one of the external metallic layers, reacts by increasing its thickness in the direction of advancement of the penetrating material, thus increasing the protective capacity of the external metallic layers.

The behavior of the reactive layer is obtained through the use of a weakened detonating material.

An aspect of the present invention refers to a system of active ballistic protection having the characteristics of original claim 1 of U.S. patent application Ser. No. 12/816,895, incorporated above by references.

Other embodiments of the panel are exemplified by the original dependent claims in U.S. patent application Ser. No. 12/816,895.

BRIEF DESCRIPTION OF DRAWINGS

To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. While some of the drawings are schematic representations, at least some of the figures may be drawn to scale. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

FIG. 1 schematically shows an exploded view of a panel of the system of active ballistic protection according to the present invention;

FIG. 2 shows an embodiment of the system according to the present invention provided with two panels parallel to each other and inclined with respect to the incoming direction of a menace, such as a projectile; and

FIG. 3 shows an embodiment of the system according to the present invention provided with two panels parallel to each other, including a spacer element and a passive element between the two panels.

DETAILED DESCRIPTION

With reference to the abovementioned figures, the system according to the present invention can be used as reinforcement and armor-plating panel for vehicles or for fixed stations.

The kind of menace for which the system gives protection is a menace brought by material which is sent or projected at high speed in the direction of the station to be protected. For example, the menace may be a melted or semi-melted metallic material constituted by one or more projectiles fired by rocket launchers or similar firearms, or shaped charge jets, generated by static blasts.

As illustrated in FIG. 1, the system according to the present invention comprises at least one panel 1 formed by at least two external metallic layers 2 and 3 between which a layer of energetic material 4 is inserted. Energetic material 4 may comprise, for example, a weakened detonating material. The weakened detonating material has the characteristic of “reacting” by expanding once the menace, for example the projectile, has perforated an external metallic layer 2 or 3.

The two metallic layers 2 and 3 of the sandwich are preferably comprised of two plates having a lateral size and thickness of about 2 mm.

For containing the sheet of energetic material, the two metallic layers or plates 2 and 3 are preferably separated by a frame 5, which may comprise for example nylon, along the entire rim. The assembly may be provided with passing holes 8 to facilitate assembly.

A suitable energetic material that may be used according to the present invention is the explosive PBX N109, as basic energetic material from which it is possible to obtain the weakened detonating material, e.g., by partially or entirely eliminating the content of aluminum normally contained in PBX N109 and by diminishing the weight percentage of RDX with respect to the inert ligands normally contained in PBX N109, which ligands may comprise for example polyurethanic ligands. A suitable percentage of RDX of diminished content comprises between about 30% and about 50%, preferably about 40% with respect to the ligands contained in PBX N109.

FIG. 2 illustrates an exemplary system comprising two panels arranged parallel to each other and separated one from the other by means of a spacer element 6. According to one embodiment, the panels can be inclined with respect to the incoming direction of the menace and arranged inside a metallic box body 7. A suitable inclination angle of the panels is between about 20° and about 40°, preferably about 30°.

It will be appreciated that different numbers of panels can be used with different geometric arrangements, and furthermore there can be present other passive elements elements 8, such as in an embodiment of the invention illustrated in FIG. 3.

As is well-known in the explosives art, the term “PBX” is an acronym for “polymer-bonded explosive”. The term “PBX N109” (also known as “PBXN-109” or “PBX 109”) is a polymer-bonded explosive (PBX) composed of: 64% RDX (Research Department Explosive), 20% aluminum, and 16% binder (e.g., “ligands” or “inert ligands,” such as polyurethanic ligands).

The term “RDX” is an acronym for “Research Department Explosive” (also known as “Research Department Formula X”), which has the IUPAC name 1,3,5-trinitroperhydro-1,3,5-triazine, the empirical chemical formula C₃H₆N₆O₆, and the following chemical structure:

Other chemical names for RDX include 1,3,5-trinitro-1,3,5-triazacyclohexane; 1,3,5-rinitrohexahydro-s-triazine; and cyclotrimethylenetrinitramine. Other names for RDX include “cyclonite” and “hexogen.”

Additional details regarding the composition of PBX N109 and methods for manufacturing PBX N109 are set forth in the following articles, which are incorporated herein by reference: Flynn, “Application of Integrated Trials Techniques for Blast Analysis of PBX Materials,” 2006 Insensitive Munitions and Energetic Materials Technology Seminar; Hamshere, et al., “Evaluation of PBXN-109: the Explosive Fill for the Penguin Anti-Ship Missile Warhead,” DSTO-TR-1471 (August 2003); and Lochert, et al., “Evaluation of Australian RDX in PBXN-109,” DSTO-TN-0440 (June 2003).

According to Hamshere et al., the polyurethanic binder component (inert ligands) can be made by reacting together the following “binder precursors” (or “binder ingredients”): hydroxyl-terminated polybutadiene (“HTPB”) and isophorone diisocyanate (“IPDI”), optionally together with other inert components, such as dioctyl adipate (DOA) (a plasticizer), di-(2-hydroxyethyl)-5, 5-dimethylhydantoin (“Dantocol DHE”), antioxidant, and triphenyl bismuth.

Hamshere et al. further teach that PBX N109 can be made by (1) forming a slurry containing RDX, aluminum, and the binder precursors HTPB, IPDI, DOA, antioxidant, Dantocol DHE, and triphenyl bismuth in the amounts shown in Table 1 below, (2) casting the slurry into a mold, and (3) permitting the slurry to react and harden into PBX N109. The diisocyanate curing agent (IPDI) can be added last to prevent premature curing.

TABLE 1 Ingredient Nominal wt % RDX (Class 1) ≧57¹   RDX (Class 5) ≦7¹   Aluminum 20    HTPB  7.346 IPDI  0.9465 Dioctyl adipate  7.346 Dantocol DHE 0.26 Anti-oxidant 0.10 Triphenyl Bismuth 0.02 ¹total RDX = 64%

The RDX used in making PBX N109 may be composed of Type II, Class 1 and Type II, Class 5 RDX, which denote the grain size of the RDX particles but may share the same chemical composition. Hamshere et al. teach that the RDX used in making PBX N109 can be provided as CXM-7, which consists of RDX (94.5 to 96.0 wt %) coated with dioctyl adipate (DOA) (4.0 to 5.5 wt %). Hamshere et al. further teach that the process that yields Type II RDX also produces HMX as a byproduct such that CXM-7 contains 5 to 12% of this material. “HMX” has the IUPAC name octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, the empirical chemical formula C₄H₈N₈O₈, and the following chemical structure:

Another name for HDX is “octogen.”

In view of the foregoing, the composition of PBX N109 may be composed of: 64% of RDX (or RDX and HMX) (“total explosive”), 20% aluminum, and 16% binder (e.g., “ligands” or “inert ligands,” such as polyurethanic ligands).

Energetic material 4 may be a weakened explosive or detonating material, such as a weakened polymer-bonded or polymer-based explosive made by reducing the amount of total explosive normally contained in PBX N109 to form a weakened detonating material and at least partially eliminating aluminum normally contained in PBX N109. A weakened version of PBXN-109, suitable for use as the energetic material 4 depicted in FIG. 1, may be obtained from standard PBXN-109 by altering the standard composition shown in Table 1 above.

By way of example, the total explosive (RDX or RDX+HMX) in the weakened detonating material can be less than 35% by weight of the explosive, preferably less than about 33% by weight, more preferably less than about 30% by weight, and most preferably less than about 25% by weight of the explosive. The balance of the composition can be binder (e.g., polyurethanic binder and/or inert ligands normally contained in PBX B109) and optionally aluminum in an amount of less than 20%, preferably less than about 10%, more preferably less than about 5%, and most preferably less than about 2% (e.g., 0%).

By way of further example, when the amount of aluminum is 0% and the amount of RDX (or total explosive) in the composition is between about 30% and about 50% by weight of the binder (e.g., the “inert ligands normally contained in PBX N109”), the amount of RDX (or total explosive) in the composition is between about 23% and about 33% by weight of the explosive composition. When the amount of aluminum is 0% and the amount of RDX (or total explosive) in the composition is about 40% by weight of the binder, the amount of RDX (or total explosive) in the composition is about 28.6% by weight of the explosive composition.

FIG. 2 illustrates a system comprising two panels arranged parallel to each other and separated one from the other by means of a spacer element 6. According to one embodiment, the panels can be arranged inside a metallic box body 7. A surface of the metallic box body 7 may be oriented normal to the direction of an incoming menace. The panels 1 may be inclined with respect to the surface of the metallic box body 7 and, therefore, the direction of the incoming menace. A suitable inclination angle of the panels 1 relative to the surface of the metallic box body 7 is between about 20° and about 40°, preferably about 30°.

It will be appreciated that different numbers of panels can be used with different geometric arrangements, and furthermore there can be present other passive elements.

The terms “approximately,” “about,” and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and/or within less than 0.01% of a stated amount.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

What is claimed is:
 1. An apparatus for active ballistic protection, comprising: at least one panel comprised of at least two external metallic layers; and a layer of energetic material positioned between the at least two external metallic layers, wherein said energetic material is obtained from a weakened detonating material comprised of an inert component, an explosive component in an amount of about 30% to about 50% by weight with respect to the inert component, and optionally aluminum in an amount less than about 20% by weight of the weakened detonating material.
 2. An apparatus according to claim 1, wherein said weakened energetic material is derived from the explosive PBX N109, which contains 64% explosive, 20% aluminum, and 16% inert ligands.
 3. An apparatus according to claim 1, wherein said weakened energetic material is obtained by eliminating aluminum normally contained in PBX N109 and providing a diminished weight percentage of RDX normally contained in PBX N109 with respect to the amount of inert ligands contained in PBX N109.
 4. An apparatus according to claim 3, wherein the diminished weight percentage of RDX is between about 30% and about 50% with respect to the amount of inert ligands.
 5. An apparatus according to claim 3, wherein the diminished weight percentage of RDX is about 40% with respect to the amount of inert ligands.
 6. An apparatus according to claim 3, wherein the inert ligands comprise polyurethanic ligands.
 7. An apparatus according to claim 1, the apparatus comprising two panels arranged parallel to each other and separated from each other by means of a spacer element.
 8. An apparatus according to claim 7, wherein said panels are inclined with respect to an incoming direction of a menace.
 9. An apparatus according to claim 8, wherein an inclination angle of the panels is between about 20° and about 40°.
 10. An apparatus according to claim 8, wherein an inclination angle of the panels is about 30°.
 11. An apparatus according to claim 7, wherein said panels are positioned inside a metallic box body.
 12. An apparatus according to claim 7, further comprising one or more passive elements positioned between the panels.
 13. An apparatus for active ballistic protection, comprising: at least one panel comprised of at least two external metallic layers; and a layer of energetic material positioned between the at least two external metallic layers, wherein said energetic material is a weakened detonating material obtained by at least partially eliminating aluminum normally contained in PBX N109 and providing a diminished weight percentage of RDX between about 30% and about 50% with respect to the amount of inert binder component normally contained in PBX N109, and wherein the inert binder component comprises polyurethane.
 14. An apparatus according to claim 13, wherein the energetic material consists essentially of RDX and polyurethanic binder.
 15. An apparatus according to claim 13, the apparatus comprising a plurality of panels arranged parallel to each other and separated from each other by means of a spacer element, wherein said panels are inclined with respect to an incoming direction of a menace.
 16. An apparatus according to claim 15, wherein the panels are positioned inside a metallic box body at an inclination angle between about 20° and about 40°.
 17. An apparatus for active ballistic protection, comprising: at least one panel comprised of at least two external metallic layers; and a layer of energetic material positioned between the at least two external metallic layers, wherein said energetic material is obtained from a weakened detonating material comprised of inert polyurethanic ligands, a total explosive content of less than 33% by weight, and optionally aluminum in an amount less than 20% by weight.
 18. An apparatus according to claim 17, wherein the weakened detonating material comprises RDX and optionally HMX, and wherein the total explosive content is less than about 30% by weight of the weakened detonating material.
 19. An apparatus according to claim 18, wherein the total explosive content is less than about 25% by weight of the weakened detonating material.
 20. An apparatus according to claim 18, wherein the total explosive content is about 23% to about 33% by weight of the weakened detonating material. 